obsobject

Description:

obsobject

Obsobject #
An observable, computed objects written in Dart with built-in validation
Install #
dependencies:
obsobject: ^1.3.0
copied to clipboard
Observable #
An object will notify to all listeners/observers after its value changed.
Example:
var a = Observable('test');
a.listen(() {
print(a.value);
});
a.value = 'First test';
copied to clipboard
Output result:
test
First test
Computed #
It's an observable too, but its value will be calculated from other observable object.
It's smart to know which observable object that it's depend on, and auto rebuild value when value of dependencies has changed.
Example:
var a = Observable(false);
var b = Observable(1);
var c = Computed(() => a.value ? b.value*10 : 0);

print(c.value); //result 0, depend on only 'a';
b.value = 2;
print(c.value); //result 0, depend on only 'a'
a.value=true;
print(c.value);//result 20, depend on 'a', 'b'
copied to clipboard
Computed object is only recalculate if there are listeners on it or when access to its value.
And the calculation is a async process, so observable can change value many times, but Computed just run one
Example:
var a = Observable(0);
var b = Computed(() => a.value);
b.changed(()=>print(b.value));
for(var i=0; i<1000; i++) a.value=i;
print(b.rebuildCount); //result 1
copied to clipboard
Computed is just give readonly value, thus there are an object Commission used to read+write value
Validator #
Built-in validate:

required: value can not null, empty string, zero
email: value must be valid email address
range: check number value, string length, array length
pattern: check string matched RegExp
contains: value must in array
unique: value not exist in array
true: value must be true
custom: check value by a custom function
async: check value by a async function
all: combine and check all validators
least: combine and check all validators but it stopped at the first invalid
not: negative a validator
async: validate value by an async process

Observable has a property valid error validStatus, they're observables value of validation status.
Validator also has features:

condition: used to check something before execute validate
message: custom message, default message, support for localize
And easy way to custom or extends new validation

Example:
//use with Validator....
var email = Observable('',
validator: ValidatorLeast([ValidatorRequired(), ValidatorEmail()])
);

//use with Map data config
var email = Observable('',
validator: Validator.convert({
'least': {
'validators': {'required': 'Email is required', 'email': true}
}
}));
//current status
print(email.valid);
//current invalid message
print(email.error);
//listen on validation
email.listen(() {
if (email.valid) {
//do something
}
});
copied to clipboard
Flutter widget #


Create a statefull widget to update UI when observable change value, take look a sample here


Or use StreamBuilder with observable.stream
//observable defined in model layer or global
final count = Observable(0);

//in build context of widget
StreamBuilder<int>(
builder: ...,
stream: count.stream,
)
copied to clipboard


View more details in Wiki, API #